The present invention concerns concrete slipform paving machines that have a propelling unit or tractor from which a paying kit is suspended with which a layer of concrete is shaped and finished over the underlying ground as the propelling unit travels along a road or airfield alignment. The tractor of a concrete slipform paver has a rectilinear frame which straddles the concrete roadway or airfield pavement section that is being paved. The frame is propelled and supported on either end by crawler tracks mounted on side bolsters. These side bolsters each typically have two hydraulic supporting jacking columns, each of which connects to a crawler track, that allow the tractor frame elevation to be manually or automatically varied relative to the ground. The frame, and in particular a center module thereof, supports a diesel engine-driven hydraulic power unit which supplies power to the tractor and the paving kit.
The paving kit is conventionally suspended below the tractor frame by mechanical means, such as with hooks and a locking mechanism. The paving kit takes its hydraulic power from the power unit on the tractor. The tractor and the paving kit pass over fresh concrete placed in and distributed over its path as a relatively even and level mass that can be conveniently slipform-paved. During this process, the tractor-attached paving kit spreads the semi-solid concrete dumped in the path of the paver, levels and vibrates it into a semi-liquid state, then confines and finishes the concrete back into a semi-solid slab with an upwardly exposed and finished surface. The sideforms mounted on each side of the slipform paving kit shape and confine the sides of the slab during the slipform paving process.
The tractor normally has three or four crawler tracks, each mounted to a jacking column, supporting and propelling the frame during use of the paver in the paving direction. Other kits can be attached to these tractors such as kits for conveying and spreading concrete and trimming and spreading base materials. For the purposes of this description, the focus is on the tractor frame which carries the paving kit.
The length of the tractor frame is adjustable in a transverse direction that is normal to the direction of the paving movement to span different widths of pavements. It is known to use telescopic extensions for changing the length of the frame. Once the telescopic extension limits are reached, a bolt-in, fixed support beam extension can be added to one or both sides of the telescopic frame for further extension.
As is well known, tractor frames for slipform paving machines have a generally rectangularly shaped center module or platform which supports, for example, the power unit including the engine for the paver, an operator platform, and the like. The bolsters that connect the jacking column with the crawlers of the paver are connected to the platform with telescopic extension arms or support beams which can be retracted into the center module, to reduce the length of the paver (in a direction perpendicular to the normal paving direction), or extend it outwardly from the center module, to increase the width for paving. However, the length of the center module limits the distance over which the support beams can be extended away from the center module because a substantial portion of the support beams, typically about three to four feet, must remain secured inside the center module so that the support beams are firmly supported by the center module. It is highly desirable that the paving widths can be adjusted by as much as possible without having to disassemble the tractor frame, and to this end it is known to employ two-stage or double telescopic support beams which, in their collapsed position, nest within each other, as is well known in the art. Thus, there are now slipform pavers on the market which employ a two-stage tractor that can vary the length of the tractor (in a direction normal to the paving direction) over a range between a minimum of about eight feet, three inches (2.5 m) to about twenty feet (6.10 m). If the paver is to lay down a strip of concrete that is wider, it is necessary to partially disassemble the frame to install one or more fixed frame extensions between the ends of the support beams (that are telescoping or not) and the bolsters of the paver to which the jacking columns with the crawlers are mounted. While it is relatively simple and not very time-consuming to change the length of the tractor frame by moving the telescoping support beams in or out, installing bolt-in, fixed support beam extensions to increase the length of the frame past its maximum width attainable with the telescopic support beams significantly increases the time, complexity and difficulty of changing the width of the tractor frame.
Thus, it is highly desirable to construct the tractor frame so that its width can be increased as much as possible with the telescoping support beams to thereby reduce the frequency with which bolt-in, fixed support beam extensions must be installed, which in turn enhances the efficiency and profitability of the paver.
Pavers which employ two-stage, hydraulic, double telescopic extenders with which the maximum length of the tractor frame can be increased without the need for installing fixed frame extensions simplify extending the length of the support beams for a greater paving width. The drawback of such arrangements is that two-stage, hydraulic, double telescopic extenders are complicated, costly to build and maintain, and are difficult to keep from deflecting under vertical loads, thereby reducing the effective paving capability of the paver.
It is a principal object of the present invention to streamline and speed up changing the width of the tractor frame of a slipform paving machine by increasing the range over which the bolsters of the machine can be extended by means of moving the telescoping support beams in or out in a simple, effective and inexpensive manner to thereby reduce the frequency with which bolt-in, fixed support beam extensions must be installed.
This is attained with an adjustable width paving machine that moves in a travel direction for spreading, leveling and finishing concrete into a form having a generally upwardly exposed, finished concrete surface and terminating in lateral concrete sides. The paving machine has a main tractor frame including a center module, a bolster next to each lateral end of the center module, and first and second crawlers connected to jacking columns which are secured to each bolster. The crawlers are pivotable about substantially vertical axes of the jacking columns between the travel direction and a lateral direction that is transverse to the travel direction.
First and second telescopic support beams are firmly attached to an inner side of each bolster that faces the center module. Each beam has a length greater than a minimum distance between the inner sides of the bolsters so that free ends of the support beams extend past the respective inner sides of the bolsters and, preferably, past the outer side of the bolsters. Each bolster has openings formed to receive and permit passage of the free ends of the support beams attached to the other, opposite bolster past the inner side of the bolster to which the support beams are not attached.
When the width of a concrete strip laid down by the paving machine must be changed, the length of the main frame, which can be changed between a minimum length at which inner sides of the bolsters facing the center module are closest to the center module and a maximum length at which the inner sides of the bolsters are farthest apart from the center module, at least one, and typically both, of the bolsters and the support beams attached to them are moved in the lateral direction relative to the other bolster and relative to the center module as needed. Depending on the selected length of the main frame in the lateral direction, the support beams attached to the bolsters will extend through associated openings in and past outer sides of the other bolster when the main frame has its shortest length. When the main frame is fully extended in the lateral direction, the free ends of the support beams are retracted inside the passages in the center module.
As is described in detail below, this change in the length of the tractor frame is preferably performed in accordance with the present invention by moving one or both of the bolsters relative to the center module with the crawlers of the respective bolsters. This change is fast and effective, saves machine down-times during the change, and thereby enhances the efficiency of the paver.
Referring initially to
The respective bolsters can be moved in the lateral direction so that the machine frame, including the crawlers, straddles a paving kit 17 that extends over, clears and forms a strip of concrete (not shown) being laid down by the machine. When finished, the strip of concrete defines an upwardly exposed, appropriately leveled and finished concrete surface (not shown) that extends across the strip between the upright sides of the concrete strip.
In use, the paving machine is aligned with the travel direction 18 so that the concrete strip can be laid between the crawlers 16 of the machine over a width determined by a paving kit suspended from the main tractor frame. Fresh concrete is deposited in front of the machine, a spreader plow or a spreading auger (not shown) approximately levels the concrete over a major portion of the width of the concrete strip, and, as the machine advances forwardly, a metering gate substantially evenly spreads the top of the fresh concrete. Following the “liquification” of the concrete by vibrators supported by a vibrator rack at a fixed elevation on the front side of the paving kit, finishing pans (not shown in
Following the completion of the concrete strip, the paving machine is typically diverted to a new site for laying another strip of concrete. When the width of the next concrete strip differs from the width of the strip that had just been laid down by the machine, it is necessary to change, e.g. lengthen, the span of the machine and the paving kit (in a lateral direction perpendicular to the travel direction 18) by correspondingly extending (or shortening) the length of the tractor frame 4 (and of the paving kit suspended from the frame), as is described in the following.
Referring to
In the preferred embodiment of the invention, two elongated, spaced-apart support beams 10 are secured to an inner side 30 of each bolster (which faces center module 6) with bolting flanges 32. The support beams are positioned on the bolsters so that they are aligned with the respective passage halves in the center module assigned to them, and they have a length so that, when the bolster side 30 to which they are attached is as close as possible to the end plate 20 of the center module, their free ends 36 extend past the center module 6 towards and past the other bolster when it too is as close to the center module as possible (as shown in
Thus, support beams 10 have a length so that when the inner sides 30 of the bolsters have a minimal spacing between them, that is, when each bolster is as close to center module end plate 20 as possible (substantially as shown in
In an alternative embodiment (not shown), if the bolsters 12 were lengthened, an additional single box beam 22 with divider plates 28 complete with support beams 10 which can slide past each other (not shown) having the required rigidity can be attached between each longer bolster to provide additional structure for the longer bolsters.
The effective length of tractor frame 4 (in the lateral direction) can be changed by moving the bolsters 12 towards or away from center module 6 until the distance between inner sides 30 of the bolsters has the required length for supporting the paving kit used for forming a concrete strip of the desired width. Tractor frame length adjustments are made by slidably moving either one or both of the bolsters relative to the center module with the support beams.
In this context, it is to be noted that the inward or outward movement of the bolsters relative to the center module need not be the same and, if desired, the bolsters can be moved so that the center module is, for example, not at the center (as shown in
Each support beam 10 has a length sufficient to extend from inner side 30 of the bolster through passage 24 in the center module, through and beyond openings 34 in the bolster that is opposite from the bolster to which the beam is attached so that the free end 36 of the beam protrudes past outer bolster side 38 as is illustrated in
Referring now to
When it is necessary to increase the span of the paving machine in order to lay down a wider concrete strip, bolsters 12 and the crawlers 16 carried by them are moved laterally outwardly to the positions shown in
To maintain structural stability, an inboard end section 48 of extended support beams 10 in
In the past, the maximum distance by which the bolsters could be moved laterally away from the center module equaled the lateral length of the center module less the support beam section 48 that must remain inside the center module passage 22. This maximum extension distance could be further increased only by using the earlier mentioned bolt-in, fixed support beam extensions, which is a time-consuming process to add and remove. With the present invention, the maximum effective length of the tractor frame that can be reached telescopically is substantially increased as compared to prior art pavers. Typically the effective maximum width of the main tractor frame 4 constructed in accordance with the present invention can be increased by up to about two feet per bolster on each side for a total of approximately four feet for the whole paving machine.
Referring briefly to
Referring to
As mentioned, to facilitate sliding support beams 10 in and out of support beam passages 24 in center module 6, rollers 56 can be installed on the top and lower surfaces 52, 54 of the center module, and the center module is provided with a hole (not separately shown) through which rollers extend so that their respective peripheries engage the upper and lower surfaces, respectively, of the support beams 10 arranged side-by-side in each passageway 24. In the embodiment of the invention illustrated in
Providing the friction-reducing rollers 56 is a presently preferred embodiment of the invention. The rollers significantly reduce friction between support beams 10 and passageway 24 when moving the support beam into or out of the passageway so that the center module 6 can be carried by crawlers 16 and the bolsters 12 and support beams 10, which eliminates the need to place separate supports 40 beneath the center module as schematically shown in
Still referring to
In an alternative embodiment of the present invention, locking mechanism 46 is defined by an appropriately shaped plate, schematically identified in
As previously mentioned and referring to
A dowel bar inserter 70 is positioned rearwardly of main tractor frame 4 and center module 6. To movably support the dowel bar inserter from the paving machine, which is required for properly inserting the dowel bars into the freshly placed concrete, the lateral ends 74 of a cross beam 72 are tied into, that is, they are typically bolted to, rearwardly extending bolster extensions 76. The forward ends of the bolster extensions are secured to main tractor frame bolster 12, and its aft ends are suitably connected to the aft jacking columns 14 which mount aft crawlers 16.
Cross beam 72 for supporting dowel bar inserter 70 comprises a telescoping, laterally extendable and retractable support system that has a center housing 6′ which, on its interior, defines a pair of open-ended, parallel passageways (not separately shown in
The dowel bar inserter 70 is movable (with wheels, not separately shown in
When dowel bars are to be inserted into the fresh concrete, cross beam 72 (which is part of the dowel bar inserter) is necessary to provide structural stability to the bolster extensions 76 which provide space for the dowel bar inserter to operate as well as room for the cross beam. The support beams 10′ of cross beam 72 are extended inwardly or outwardly, as needed, so that the aft jacking columns 14 are at the desired positions and the cross beam has the required length (transverse to the travel direction 18) for attaching the dowel bar inserter thereto in a conventional manner.
In the preferred embodiment of the invention, cross beam 72 is constructed analogously to center module 6 as far as the lateral expandability of the cross beam is concerned. Thus, an elongated, spaced-apart support beam 10′ is secured to the inner side of each rearward bolster extension 76 with bolting flanges (not shown in
Thus, support beams 10′ also have a length so that when the inner sides of the rearward bolster extensions 76 have a minimal spacing between them, which occurs when each bolster 12 is as close to center module end plate 20 as possible (substantially as shown in
When it is necessary to change the paving width of the machine, support beams 10 and 10′ are moved relative to center module 6 and center housing 6′ until the desired width has been reached. Thereafter all beams are secured to the center module and housing, preferably in the above-described manner. Simultaneous therewith, the length (in the transverse direction) of dowel bar inserter 17 is correspondingly adjusted by lengthening or shortening it as needed so that its wheels (not shown in
Number | Name | Date | Kind |
---|---|---|---|
3970405 | Swisher et al. | Jul 1976 | A |
5590977 | Guntert et al. | Jan 1997 | A |
5615972 | Guntert et al. | Apr 1997 | A |
5647688 | Guntert et al. | Jul 1997 | A |
5941658 | Dahlinger et al. | Aug 1999 | A |
6082927 | Dahlinger et al. | Jul 2000 | A |
6471442 | Deeb et al. | Oct 2002 | B1 |
6481923 | Casters | Nov 2002 | B1 |
6481924 | Smolders et al. | Nov 2002 | B1 |
6582152 | Leone et al. | Jun 2003 | B2 |
6872028 | Aeschlimann et al. | Mar 2005 | B2 |
Number | Date | Country | |
---|---|---|---|
20110194898 A1 | Aug 2011 | US |